Spatial pattern of tree species, sizes and ages affects functional processes and biodiversity of forest ecosystems. Therefore, it is more and more important that stand structural diversity can be assessed through easy-to-implement methodologies at forest management scale. This paper discusses the application of a recently proposed index (the Winkelmass index) of tree spatial aggregation, based on the measurement of the angles between neighboring stems, to a beech (Fagus sylvatica L.) forest in Northern Latium (Italy). Results shows that the Winkelmass index can be implemented in a simple and fast way according to objective sampling schemes and allows to produce a raster map of tree aggregation pattern in the forest. Under the stand condition in the test area, only four trees at each sample point were sufficient to characterize prevailing stand horizontal structure....more